Part IlI : Pig and Piglike Species

In parts of Asia wild and feral pigs are often the most abundant source of meat. These animals are predominantly variants of the domestic pig, Sus scrofa, or of its ancestor, the Eurasian wild boar. Also contributing to the pig population are five Asian species:

· Bearded pig

· Sulawesi warty pig

· Javan warty pig

· Pigmy hog

· Babirusa

In Southeast Asia hybridization between these species and common pigs has resulted in a confusing diversity of forms and interrelationships. Because of their value, these pigs have been spread since prehistoric times by traders and migrating peoples, creating odd and unpredictable distribution patterns.

The species listed represent a gene pool of potential importance for the further development of one of man's most important sources of food.

In many areas of the world, one must start with the native animals adapted to that environment. In many cases, they are the only animals the native human population can afford to begin with. And it is amazing the increased animal production that can result from the use of better production practices with them. TONY J. CUNHA, Dean Emeritus California State Polytechnic University Pomona, California, USA

Fitting the animal to the vegetation might be a better approach than trying to fit the vegetation to the animal, especially on ranges that have been changed or degraded by man. JAMES TEER, Director Texas Parks and Wildlife Department, Austin, Texas, USA

There is now widespread realization that breed importation is not necessarily the quickest route to increased animal production. Indigenous, adapted breeds should be examined more closely and, where necessary, steps should be taken to ensure conservation of at least some of them. HELEN NEWTON TURNER Genetics Research Laboratories, CSIRO, North Ryde, New South Wales, Australia

Maximizing the animal harvest, essentially of animal protein, assumes in concept that all animals will be fully exploited in efficient and economic production systems. C.DEVENDRA Malaysian Agricultural Research and Development Institute, Selangor, Malaysia

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11 The Bearded Pig

Although it apparently has never been domesticated, the bearded pig (Sus barbatus) has a long history as an important resource in Southeast Asia. Human remains from the Niah Caves in Sarawak are accompanied by large numbers of its bones and teeth, indicating that 40,000 years ago it was the most commonly eaten large animal. Today in Sarawak and some other areas the bearded pig is still probably the most sought after source of wild meat.

Appearance and Size

Bearded pigs are large. Boars measure 1-1.6 m in length (crown to rump), up to 1 m in height, and may weigh as much as 150 kg. Sows are smaller. Adult males have small facial warts (infraocular and preocular) and a bushy tuft of hair on the cheek. Both sexes vary in color from pale red-brown to yellow-brown or black. They have elongated skulls with longer, more flexible snouts than the common pig.

Distribution

Five subspecies are recognized. They range through the Philippines (Balabac, Palawan and offshore islands, Calamianes, Luzon, Mainit, Mindanao, Jolo, Mindoro, and Cebu) to Borneo, Bangka, Sumatra, the Riau Archipelago, and the Malay Peninsula.

Status

The Borneo subspecies (Sus barbatus barbatus) is still abundant in some parts of Sabah, Sarawak (including several wildlife reserves), and

Kalimantan. It remains an important food resource for some hill tribes, although with the spread of Islam, attitudes toward pork are changing in some areas. The Malayan subspecies (Sus barbatus of) is now rare in the Malay Peninsula. It is also becoming rare in Sumatra as the lowland forests are logged and broken up by commercial interests and as the human population expands. The status of the three Philippine subspecies is currently unknown.

Habitat and Environment

The bearded pig is most commonly found in both primary and secondary evergreen forests. However, it seems to have wide adaptability, and in Sarawak bearded pigs are found in virtually all habitats from the beaches to the upland rain forests.

Biology

No biological research has yet been conducted on bearded pigs, but naturalists have made several observations. The pigs eat the seeds of trees (for example, those of species of Dipterocarpaceae and Fageceae), fallen fruits (of Moraceae, Bombacaceae, and other plant families), roots, stems of wild bananas, herbs, and probably earthworms, and along the coast they dig up and eat turtle eggs.

Births occur throughout the year in Sabah, but the peak coincides with the fruiting season of forest trees, usually August-September. The litter size is from 3 to 11 piglets.

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Behavior

No behavioral studies have been conducted, but observations suggest that bearded pigs are generally sedentary animals, although in some areas they congregate into large groups that may travel long distances together.

Uses

The species might be used (alone or together with other pig species) as a local source of meat, or even as the foundation of a meat industry. The bearded pig is accustomed to living in groups, which may make it suitable for husbandry or game management.

There is evidence that the bearded pig will interbreed with the common pig, producing young in which both sexes are fertile.* The progeny might have considerable hybrid vigor.

Potential Advantages

The bearded pig may have tolerance (if not actual resistance) to tropical diseases and conditions that affect the common pig. The species survives in areas of Southeast Asia where feral herds of common pigs are not common, apparently owing to their inability to cope with disease or other environmental challenges.

Limitations

No negative qualities have been reported, but the animal's biology, behavior, management, and potential uses are so far virtually unstudied.

Research and Conservation Needs

Aspects of the animal's general biology that should be investigated include:

· Chromosome type and variability, and chromosomal differences between the bearded pig and other wild and domesticated pig species

· Reproductive physiology

· Nutritional physiology

· Social behavior (both in its wild state and under controlled conditions).

To assist in the selective capture of young bearded pigs in the wild, external features that characterize the species at an early age need to be identified.

To assess the bearded pig's potential for contributing hybrid vigor, crossbreeding with other pig species should be attempted under controlled conditions.

12 The Sulawesi Warty Pig

The Sulawesi warty pig (Sus celebensis) is one of the world's few domesticated animals. It is maintained as a village or household animal in a few areas of Southeast Asia, such as on the Indonesian island of Roti. The common pigs of New Guinea and parts of the Moluccas group are hybrids between this species and the common pig.

Appearance and Size

Sulawesi warty pigs are medium sized, averaging about 60 cm high and 40-70 kg. Boars are larger than females and have longer (10 cm) tusks on both jaws. Boars have three pairs of prominent facial warts: on the snout, the cheek, and on the angle of the jaw. In sows these warts are small or absent entirely.

The animals are usually red-brown with sharply marked white and yellow undersides; older animals have a round white spot (about 3 cm in diameter) on each side of the upper cheek. Piglets have horizontal stripes on the body, which disappear as they mature.

The body is covered with scanty coarse hair, but stiff bristles, which become erect when the animal is alarmed, occur along the mid-dorsal line of the body. The longest and stiffest occur on the head and nape.

Distribution

Native to mainland Sulawesi and certain surrounding islands, the Sulawesi warty pig has been introduced to the Lesser Sunda Islands (Flores, Sumba, Roti, Semau, and Timor), the Moluccas (Malmahera and Buru), and Simaleue, a small island west of Sumatra. In some parts of the Philippines (for instance, Naujan and Mindoro Oriental) the animal either occur naturally or has been introduced.

Hybrids between the Sulawesi warty pig and the common domestic pig occur on New Guinea, Ternate, Morotai, Bacan, Amron, Seram, Kei island, Aru island, and Sulawatti.

Status

In many islands of eastern Indonesia, this species is widespread and common. In a few places it is extremely abundant, particularly at higher altitudes; in others, it has been greatly reduced by overhunting, deforestation, and expanding human settlement.

Overall, however, Sulawesi warty pig populations are declining, probably due to increased hunting and to human alterations of the animal's habitats.

Habitat and Environment

This pig inhabits varied environments, including rain forest, mountain forest, grasslands, and agricultural areas.

FIGURE

 

Biology

Like the common pig, the Sulawesi warty pig has broad dietary preferences. It feeds on roots, fallen fruit, leaves, and young shoots. The bulk of its food consists of vegetable materials, but it also feeds on earthworms, insects, aquatic invertebrates, rats, birds, and even carrion.

The uterus and placenta are anatomically indistinguishable from those of the common pig. The litter size is from 2 to 8 piglets, with an average of 5.

Sows can give birth throughout the year, but usually have their young in April or May. The gestation period is about 4 months.

Behavior

Breeding and farrowing occur in the forest and in open Imperata cylindrica grasslands. The pregnant female makes a nest of grasses, leaves, twigs, and branches, which she collects and places over a hole (approximately 2 m long) that she has previously dug. Here she gives birth.

Foraging is the main activity of the day and usually takes up several hours, mainly in the early morning and evening. In the wild the pigs travel in small groups, the young always traveling with an adult female. On the move, warty pigs feed and rest intermittently.

Uses

As a source of meat the Sulawesi warty pig has been recognized and exploited by local populations since prehistoric times. The presence of feral specimens far outside the pigs' natural range indicates that traders or migrants have long carried it with them on voyages, either as domestic stock or as wild specimens to be released for later capture.

The tusks, which can be carved like ivory, are a resource for local artisans. Wild specimens are suitable for sport hunting.

Potential Advantages

There is a body of unrecorded indigenous experience with this animal as a domesticate, but the information needs to be collected and appraised.

The Sulawesi warty pig may be expected to possess resistance or tolerance to the many diseases prevalent in its native habitat.

There is promising potential for hybridization between this species and domestic pigs, which might lead to the improvement of common pigs in tropical regions.

Limitations

Apart from the unwritten knowledge of the indigenous people who raise the species, very little information is available on the characteristics and management of this animal.

Research and Conservation Needs

The genetic variability within the species, as well as the karyotypic differences with common pigs and other Sus species, should be defined. Further, the hybrid vigor resulting from crossbreeding with other Sus species should be- quantified under controlled conditions. Apart from producing potentially important heat-tolerant livestock, crossbreeding may shed important light on the origins of the common pig in Asia.

The animal's nutritional requirements and reproductive biology also need study.

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13 Javan Warty Pig

The Javan warty pig (Sus verrucosus) apparently has never been domesticated, but it has been a resource for hunting peoples for centuries. Now, however, the human population in its native region is predominantly Moslem, and all pigs are widely regarded as agricultural pests. Increasing numbers of them are poisoned each year.

Appearance and Size

The Javan warty pig can be up to 1.35 m long and 0.9 m tall. Mature males usually weigh between 80 and 120 kg; females are only half that weight - an unusually dramatic example of sexual dimorphism. The animal has a markedly elongated face with large warts, particularly the infraorbital wart and the smaller preorbital and mandibular warts. Body hairs can be black, red, or yellow, with black tips.

Distribution

This species is found only on the Indonesian islands of Java and Bawean. It was formerly found on Madura as well, but because of deforestation it is now thought to be extinct there. Two extant subspecies are recognized. The nominate one, Sus verrucosus verrucosus, occurs on mainland Java. The second, Sus verrucosus blouchi, a smaller animal, has recently been described on Bawean.

Status

For years it was thought that the Javan warty pig was extinct in the wild, but in October 1981 a herd was found in a small area on Mount Penanggungan in East Java. This population may prove to be substantial, and there is reason to hope that other populations can be found. Overall, however, it is clear that the Javan warty pig is endangered and declining in numbers. In many areas the animals are subjected to uncontrolled poisoning and hunting.

Five new reserves have recently been proposed to protect the animal in a variety of habitats because it is not found in appreciable numbers in any of Java's nature reserves.

The Bawean subspecies is believed to be relatively secure since the establishment of a large reserve.

A breeding colony of 12 Javan warty pigs at the Surabaya Zoo includes 5 young ones born in captivity.

Habitat and Environment

Habitats of the Javan warty pig appear to be confined to elevations below about 800 m. The animals prefer relatively large expanses of grassland or secondary vegetation, where human population is sparse.

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Biology

The piglets can be born throughout the year; in one study of 8 sows the litter size ranged from 2 to 8, with a mean of 5.

The (diploid) chromosome number has been found to be 38, the same as that of the common pig. Hybridization between these species is thought to occur in the wild, but apparently not with enough frequency to contaminate the Javan warty pig gene pool.

Behavior

Unreported.

Uses

These are omnivorous, adaptable animals that might make useful domesticates.

Potential Advantages

The small size of the sows could make this species particularly appropriate for households or smallholder farms. The animal's genetic "distance" from the domestic pig may make it a useful generator of hybrid vigor in crossbreeds. It could have particular value because its meat is much leaner than pork from the common pig.

Limitations

The numbers in the wild are now too few to permit any cropping.

 

Research and Conservation Needs

Efforts should be directed towards locating and breeding up the Javan warty pig populations that still exist. An immediate need is to isolate pure populations in reserves because it is essential to protect the animal from crossbreeding with other species. In addition, current specimens in zoos should be cataloged and a breeding program established. Other captive breeding colonies should also be started.

It is important to determine the genetic differences between the Javan warty pig and the common pig, as well as the levels of existing hybridization between them. It is also necessary to determine what variation in karyotype may exist within the populations.

Basic ecological and behavioral studies are needed, as well as studies of the dietary requirements, growth rates, and nutritional physiology of captive specimens. The reproductive biology of the animal should be studied, and the possibility of crossbreeding it with other Sus species should be examined under controlled conditions.

The Javan warty pig's potential for local meat production should be evaluated. The benefit to rural people of converting an agricultural pest into a profitable source of income should be explored within the local religious context.

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14 Pigmy Hog

The pigmy hog (Sus salvanius), a shy and very small pig of northeastern India, is close to extinction because of hunters and the destruction of its habitat.

Appearance and Size

The pigmy hog is only about 60 cm long, with a shoulder height of about 25 cm and a body weight of less than 10 kg. The hair is medium brown on the sides, darkening to blackish brown along the mid-dorsal line. A facial band of short, dark hair extends from the bridge of the nose to below the eye. The tiny tail is only 3 cm long.

Distribution

This animal was once widely found along the southern foothills of the Himalayas; today, it is definitely known to occur in only one area, the Manas National Park in Assam.

Status

Pigmy hogs are seriously endangered; in the wild they are close to extinction. Captive animals are now reduced to a single male in the Assam State Zoo and four male siblings in the Zurich Zoo.

Habitat and Environment

The few remaining pigmy hogs mainly inhabit tall-grass savannas, but it seems likely that they could adapt to other environments.

Pigmy hog. (W.L.R. Oliver)

Biology

The animal is omnivorous and consumes roots, tubers, grass, leaves, insects, earthworms, eggs, and carrion. While foraging, it undoubtedly consumes large quantities of earth as well.

The chromosome number, 38, is the same as that of the common pig. The karyotype is similar to that the common pig, but small, significant differences have been demonstrated using chromosome banding techniques.*

The age at puberty, time of weaning, length of gestation and estrous cycle, and season of breeding are not yet known with certainty. However, the animal is known to have a single well-defined birth peak (April/May) that coincides with the onset of the rainy season when the food supply increases. The uterus and placenta are anatomically similar to those of the common pig. The litter size varies from 2 to 6. It is not known if the animal can be crossbred with the common pig.

Distribution of pigmy hog. (W.L.R. Oliver)

Behavior

The animals are shy, but can be tamed. They tend to forage and run in groups. Nest building is carried out by both males and females and is not restricted to pre-farrowing periods.

Uses

There is no evidence that the pigmy hog has ever been domesticated; it has, however, been extensively hunted and trapped, and recently it was still being sold for human consumption. There would probably be no inherent difficulty in maintaining this species in husbandry.

Potential Advantages

The pigmy hog's small size may make it useful in studies of the physiology of pigs and like mammals. In particular, a study of the uterine capacity may contribute to our understanding of the maternal factors that influence the number and size of mammalian young at birth.

It is unknown if the animal carries genetic resistance to diseases of the domestic pig, but given its habitat, such resistance seems likely.

Limitations

The small numbers of surviving pigmy hogs obviate any consideration of its use in husbandry at the present time. Moreover, its nervous temperament might restrict its potential as a domesticate.

Research and Conservation Needs

It is essential to ensure the survival of this animal. Efforts should be directed towards locating and breeding up the populations that still exist. If its habitat could be protected by preventing the annual dry-season burning of grasses, it is possible that substantial populations could be established. Attempts should also be made to acquire two or more females as mates for the male pigmy hogs at the Assam and Zurich zoos.

There is also an urgent need to ensure that the animals breed successfully in captivity, and the wealth of international expertise in pig reproduction should be applied to that end. For example, the reproductive biology of the animal could be studied by swine experts; the age at puberty, the length of the estrous cycle, the season of breeding (and whether it is influenced by light or temperature), the length of gestation, and time of weaning all need to be determined.

The animal is an omnivore, but the physiology of its digestion has not been studied. Thus, its nutritive requirements are not well enough known to ensure its survival in captivity or reserves.

Experiments should be made to determine if pigmy hog embryos can be brought to term in the uterus of the common pig. If so, such embryo transfers could be used to distribute embryos and set up new herds, lessening the risk of this species" extinction.

Adult male of the common pig (wild boar Sus scrofa) and pigmy hog drawn to the same scale. (W.L.R. Oliver)

15 The Babirusa

The babirusa (Babyrousa babyrussa) is a piglike animal whose closest relative appears to be an ancestral animal that lived in Europe 35 million years ago. It is easily tamed, and in its native area there is an ancient tradition of raising young babirusa for meat and for the males' unique tusks. The animal appears to reproduce well in captivity, and with good management techniques it might gain wide use in the tropics.

Appearance and Size

Male babirusa can be up to 110 cm long and 80 cm tall and weigh up to 100 kg; females are smaller. The male has large upper canines that grow upwards, piercing right through the flesh of the snout and curving back and downwards towards the forehead without ever entering the mouth. The female may sometimes have small upper canines projecting through the skin of the upper lip.

The animal is more slender than a pig of similar size. It has a gray or brown-grey skin color, although one subspecies, Babyrousa babyrussa babyrussa, has light body hair that is fawn colored or black.

Distribution

The babirusa is unique to a few islands of eastern Indonesia: north, central, and southeast Sulawesi, the Togian Islands, and the Sula (Taliabu and Sulabesi) and Buru Islands. On Sula and Buru it is probably not native but was introduced in prehistoric times.

Status

On Sulawesi the babirusa remains abundant, despite hunting and the widespread clearing of the forest. Nevertheless, disturbances created by wood and rattan collectors, hunters, loggers, and farmers threaten the babirusa's survival. Throughout the rest of its range, it is also vulnerable to extinction.

Biologists are particularly concerned about some of the babirusa subspecies. The one from the north of mainland Sulawesi, Babyrousa babyrussa celebensis, is still relatively abundant in places and is probably in no immediate danger. The Togian Islands' subspecies, Babyrousa babyrussa togeanensis, is abundant in small islands but is threatened by Indonesia's settlement programs and deforestation. The Buru and Sula Islands subspecies, Babyrousa babyrussa babyrussa, may already be extinct; there have been no confirmed sightings in recent years.

In 1981, there were 26 male and 27 female babirusa held in six zoo collections; 22 of these animals are in the Surabaya Zoo in Indonesia, where they breed well. Most, if not all, are believed to belong to the mainland Sulawesi race.

Habitat and Environment

The animals mainly inhabit moist forests at low altitudes.

FIGURE

 

Biology

Precise details of babirusa biology are unknown, but the stomach has an extra sac, suggesting that the animals may have some ability to break down cellulose. Indeed, they browse leaves, a behavior more often found in a deer than in a pig, and have been referred to as "ruminant pigs." Babirusa also live on roots, berries, and grubs, making them true omnivores. Compared to other pigs, they do little rooting, and in captivity their enclosures remain quite grassy.

Babirusa are said to be sexually mature at 5-10 months, but this depends on nutrition. Gestation length is about 158 days. One or two young are produced although there are some reports of litters of three.

One specimen was kept for 24 years in captivity.

 

Behavior

The babirusa is a social animal that moves in groups. A retiring native of the dense jungle, it is a fast runner and swims readily. Mating behavior in captivity generally resembles that of domestic pig. Evidence from zoo animals suggests that the male must be removed from the young at birth but that by the time they are a month old the young are safe from paternal attack.

Uses

When captured young or reared in captivity, the babirusa is easily tamed. It has potential as a domesticated species, and with appropriate management may provide a useful source of meat. The meat is tasty and of good quality.

Because of its unique tusks, the skull of the male finds ready markets. This could provide additional income to farmers raising babirusa for meat. The ivory of the tusks could also be a resource for local artisans.

Potential Advantages

As noted, the anatomy of the stomach suggests that the babirusa may be able to make more efficient use of fibrous foodstuffs than other pigs.

Limitations

The babirusa produces only one or two young after a gestation period of just over five months; it may therefore take considerable time to build up herds.

Although the babirusa is easily tamed, it is not known whether it can be husbanded in large groups. Also, present lack of knowledge of the animal's nutrition may restrict its husbandry.

Research and Conservation Needs

The number of animals in the wild is decreasing, and attempts should be made to determine their exact status. Particular attention should be paid to the subspecies Babyrousa babyrussa togeanensis and Babyrousa babyrussa babyrussa. Captive breeding programs for these subspecies should be started.

When seen in longitudinal section, the stomach of babirusa presents striking similarities to that of a relatively simple ruminant such as the domestic sheep. Every part except the omasum, even including a rudimentary reticulum, is represented and occupies the same relative position. The babirusa stomach differs from that of the domestic pig chiefly in the enormous size of the diverticulum ventriculi, the prominence of the constrictions that delimit its three main divisions, and in the size and complexity of the cardia. Regions corresponding to parts of the ruminant stomach are labeled in brackets. (Information from Davis, 1940; diagram courtesy Field Museum of Natural History, Chicago.)

Wild populations should be maintained in several regions to ensure that the species" genetic base is retained. Advantage could be taken of the large number of islands in eastern Indonesia to establish reserves for the different babirusa subspecies.

Currently, little is known about the biology of the animal in the wild— its diet, social behavior, or reproductive performance are almost unstudied. In view of the relatively small number of babirusa in zoos and the scarcity of information about the animal's growth rate and general biology, coordinated studies between zoos could provide much basic information. It has been suggested that a studbook be initiated for this species.

It is clear from chromosome analysis that this pig differs markedly in its karyotype from that of other pigs. However, more anatomical and biochemical knowledge is needed.

Basic parameters of the animal's reproductive physiology are not known. Questions to be answered include:

· Can the babirusa be induced to reproduce twice per year?

· Can babirusa embryos be developed to term in the uterus of the domestic pig? If so, can the number of babirusas be rapidly multiplied in this way?

· Does the babirusa genotypic and gestation-length difference with the common pig prevent the two from successfully crossbreeding? And if crossbreeding can be achieved, will the progeny be fertile?

FIGURE